SHOCK TREATMENT

You can open your eyes now. On March 9, NBC's ER raised its blood-and-guts quotient to new heights as Anthony Edwards' Dr. Mark Greene performed a grisly C-section that saved the baby but left the mother dead. Two weeks later, the episode's shell-shocked viewers (34.4 million of them, pushing ER to No. 1) are still trading opinions-even though news reports diagnosed the plot as improbable. The network logged 400 calls in the aftermath. Only about 50 were negative and many gushed over Edwards' harrowing performance. ''Dr. Greene was being Saint Mark all year,'' says Dr. Lance Gentile, ER's medical consultant and staff writer. ''My job was to design his fall and make it big.'' And long. Notes * Edwards: ''A usual episode has 12 pages of trauma. This one had 48. We were very stressed.'' Greene isn't out of the woods yet. In the April 6 episode, he'll defend his actions to a panel of doctors. Says Edwards, ''He's going to be a little dark for a while.'' -Dan Snierson